(NEW YORK) — Hurricane Matthew brutalized the southeast coast for four days before weakening and veering out over the Atlantic Ocean on Sunday, leaving a trail of devastation that includes at least 21 dead, 1.3 million customers still without power and billions of dollars in damages.

Matthew wreaked havoc across five states on the eastern seaboard, from Florida all the way up to Virginia. The storm was downgraded to a post-tropical cyclone on Sunday as it headed east further out into the Atlantic Ocean.

Matthew brought 100 mph winds, as much as 15 inches of rain and powerful storm surges of up to 9 feet to several states. The storm disrupted the lives of millions, forcing more than three million coastal residents to evacuate, shutting down hundreds of roads including Interstate 95 in several places — a major east coast artery — while halting Amtrak service in the southeast and causing thousands of flights to be cancelled.

Initial estimates put insured losses due to Hurricane Matthew at $4 billion to $6 billion, according to CoreLogic, but this preliminary number likely underestimates the storm’s total impact. Experts say that Matthew could be the costliest storm to hit the United States since Superstorm Sandy in 2012, which had an estimated $68 billion in damages.

Nearly 750,000 customers were without electricity on Sunday night in North Carolina, by far the most of any of the five states in the storm’s path. More than 400,000 in South Carolina remained in the dark, in addition to over 308,000 in Florida and 204,000 in Virginia.

The Tar Heel state also had the most fatalities, with nine, even as officials said that number could rise as rescuers work to locate at least five missing people. Florida reported six storm-related deaths. Georgia blames the storm for four deaths and South Carolina attributed two fatalities to Matthew as of Monday morning.

Matthew knocked out power to 2.2 million customers at the storm’s peak.

In North Carolina, rescue teams continued to search for five people missing after record flooding hit the state.

On Sunday, a Coast Guard helicopter rescue team hoisted eight people to safety after rising floodwaters stranded them on rooftops. North Carolina’s National Guard also worked to transport bed-bound patients past flooded roads.

“Hurricane Matthew may be off the map, but it is still with us,” North Carolina Pat Governor McCrory said in a statement on Sunday. “The aftermath of this storm is extremely dangerous, as many inland areas are expecting record flooding in the coming days.”